Pinkeye in Cattle (IBK): Symptoms, Treatment & Prevention Guide

What Is Pinkeye?

Pinkeye is the most common infectious eye disease of cattle in North America, affecting up to 30% of U.S. beef herds each year and roughly 10% of all beef calves. It's caused primarily by Moraxella bovis, a bacterium that produces toxins damaging the cornea and conjunctiva. The disease peaks in the summer months when face flies — the main vector — are most active, though outbreaks can happen any time cattle are exposed.

Left untreated, pinkeye can cause permanent corneal scarring, ruptured eyes, and blindness. Blind cattle drop weight, can't compete at the bunk, and are significantly harder to handle. Even mild cases reduce weaning weights by 20–40 pounds through pain-induced reduced grazing. The economic cost is significant — but the good news is that early recognition and treatment resolve the vast majority of cases with no lasting damage.

Causes & Risk Factors

The primary pathogens

• Moraxella bovis — the classic cause of pinkeye; produces cytotoxins that damage the cornea
• Moraxella bovoculi — increasingly recognized as a significant player in modern outbreaks
• Mycoplasma bovoculi — often present in mixed infections
• IBR virus — damages the cornea and predisposes to bacterial infection

Risk factors that trigger outbreaks

• Face flies — the primary vector; carry bacteria between cattle
• Tall seedy grass — mechanical irritation of the cornea from grass seed heads
• UV sunlight — damages the cornea, especially on white-faced cattle
• Dust — dry lots, dusty roads, unimproved pasture
• Trace mineral deficiency — especially selenium and copper
• Stress — weaning, shipping, weather changes
• Breed susceptibility — Herefords and other white-faced breeds are most susceptible

The Four Stages of Pinkeye

Treatment Protocol

Step 1: Injectable antibiotic

Long-acting oxytetracycline (LA-200, Biomycin 200) at 4.5 ml per 100 lb subcutaneously is the standard first-line treatment. A single dose provides 3–4 days of therapeutic blood levels. For severe cases, tulathromycin (Draxxin) gives 7+ days of coverage in one dose. Retreat in 48–72 hours if the eye isn't improving.

Step 2: Subconjunctival injection (severe cases)

For Stage 3+ ulcers, a veterinarian may inject penicillin (1 ml procaine penicillin G) directly under the conjunctiva at the top of the eye. This creates a bulge that slowly releases antibiotic directly onto the infected tissue for 12–24 hours. Not for producer administration — this requires veterinary technique.

Step 3: Eye patch

An eye patch (see next section) protects the eye from sunlight, flies, and dust during healing. Patches typically stay in place 7–10 days and dramatically speed resolution.

Step 4: Isolate

Move affected cattle out of the main herd to reduce fly-mediated transmission. Continue observing the rest of the herd twice daily during outbreak periods.

Eye Patching Technique

An eye patch is one of the highest-value treatments a producer can master. Materials cost pennies per patch, and the improvement in comfort and healing is dramatic.

What you need

• Eye patch material (denim, canvas, or commercial patches)
• Superglue or eye-patch adhesive
• Scissors, gloves
• Sedation if the animal is fractious (talk to your vet)

Application steps

1. Restrain the animal in a chute with head control
2. Clean the hair around the eye of debris and moisture (dry patch = strong adhesion)
3. Cut a patch 4–5 inches in each direction — big enough to fully cover the eye and surrounding hair
4. Apply superglue to the patch edges (NOT to the eye or eyelashes)
5. Press firmly to the hair around the eye, holding 30 seconds
6. Ensure the eye can drain — leave a small gap at the bottom of the patch

A well-applied patch stays on for 7–14 days and falls off naturally as the eye heals. If a patch comes off prematurely, replace it if the eye still needs protection.

Prevention Program

Prevention is where most pinkeye programs succeed or fail. Vaccination alone rarely works if fly control is poor; fly control alone works surprisingly well even without vaccination. Attack this in priority order.

Priority 1: Fly control

• Insecticide ear tags — apply in spring, replace mid-summer if effectiveness drops
• Pour-on insecticides — every 3–4 weeks during fly season
• Insecticide dust bags at self-service oilers
• Fly traps and predator wasps around feeding areas
• IGR (insect growth regulator) mineral — prevents flies from developing in fresh manure

Priority 2: Environmental management

• Clip pastures to prevent seedy grass heads from irritating eyes
• Provide shade in every pasture — reduces UV exposure
• Rotate away from dry, dusty lots when possible

Priority 3: Nutrition

Adequate copper, zinc, selenium, and vitamin A support corneal health and immune function. See our Mineral Deficiency Guide. Chronic mineral deficiency is a major predisposing factor in operations with persistent pinkeye problems.

Priority 4: Vaccination

Commercial pinkeye vaccines (Piliguard, I-Site XP, Maxi-Guard) target M. bovis and give modest protection — typically reducing incidence 30–50%. Autogenous vaccines made from your herd's own isolates outperform commercial vaccines in most operations with chronic problems. Give the first dose 30–60 days before fly season, with a booster 21 days later.

Economic Impact

Frequently Asked Questions

This article is educational and does not replace veterinary care. All antibiotic use requires a prescription from a licensed veterinarian under a valid VCPR. Subconjunctival injection technique should be learned under veterinary supervision.